U.S. Pat. No. 4,892,506 entitled "Synergetic Speed-Variating Means as Eccentrically Operated" also granted to the applicant of this application discloses a sliding roller carrier means sandwiched between two driving disks respectively secured to a hub of bike wheel and a chain wheel, each disk having a plurality of radial slots formed in the driving disk. When it is intended to variate the bike speed, the central sliding-roller carrier means 2 must be eccentrically operated along the radial slots. However, since the length of each radial slot is quite limited by a radius of each driving disk, the variating ratio can not be greatly increased to satisfy a bike driver's desire for an optional speed variation.
The present inventor has found the limitation of his earlier granted patent, and invented the present homogeneous speed-variating means as eccentrically operated.